The aims of the proposed research are to study molecules of biological and pharmacological interest, in an effort to determine correlations of electron distributions with chemical parameters and biological activities. It has been well recognized that the electronic properties of certain functional groups (e.g., SO2NH2, NH2) influence the biological activities of molecules. In nearly all of the molecules of importance in biology, biochemistry and pharmacology, nitrogen atoms play an important role. Nitrogen-14 nuclear quadrupole resonance (NOR) spectroscopy is ideally suited to probe the electronic environment in the vicinity of the nitrogen atoms. NQR is employed to measure the quadrupole coupling constants and asymmetry parameters of the nitrogen atoms in the molecular solids. These two experimental parameters can be related to the electron densities (pi and sigma) at the site of the nitrogens. They might also be correlated with the Hammett sigma constants, measures of biological activities, tumor inhibiting ability, and other properties. NQR results in themselves are very important as a means of checking the accuracy of theoretical calculations for electron distributions in molecules of biological interest. BIBLIOGRAPHIC REFERENCES: "N14 Nuclear Quadrupole Resonance in the Barbiturates." N. S. Kim and P. J. Bray, Phys. Letters 60A, 483 (1977). "Nitrogen-14 Nuclear Quadrupole Resonance Study of Several Hydroxypyrimidines." S. N. Subbarao and P. J. Bray, in J. Chem. Phys., 1977, in press.